‘Push and pull’ trick to control armyworm

Kenya has lost approximately 15,000 ha of maize, valued at Sh1.3 billion, to the armyworm. FILE PHOTO | NMG

The destructive armyworm can be controlled by a readily available technology, a new study has shown.

The technology, dubbed “push-pull” by the International Centre of Insect Physiology and Ecology (Icipe) in a study released this week, can be deployed to different parts of Africa.

The scientists said the push-pull method is a suitable, accessible, environmentally friendly and cost-effective.

The fall armyworm is a moth that causes devastating damage to almost 100 plant species, including sorghum, rice, wheat, sugarcane and horticulture, threatening food and nutritional security, trade and family incomes.

It spreads very fast in adult stage and can move over 100km in a single night. The pest lays hundreds of eggs.

Kenya has lost approximately 15,000 ha of maize, valued at Sh1.3 billion, to the armyworm.

The annual loss could be 40 million bags of maize, valued at Sh120 billion, going by the current cost of Sh3,000 for one bag of maize. The loss is exclusive of farm input costs such as seeds, fertiliser, irrigation, pesticides and labour.

Push-pull is a cropping technology developed over the past 20 years by Icipe to control stem borer pests and the parasitic striga weeds.

Prof Zeyaur Khan, the push-pull leader at Icipe, said the method involves intercropping cereal crops with insect repellent legumes of the desmodium genus, and planting attractive forage such as napier grass as a border around this intercrop.

The intercrop emits a blend of compounds that repel (push) away stem borer moths, while the border plants emit semiochemicals that are attractive to (pull) the pests.

“Efforts to control the armyworm through conventional methods, such as use of insecticides, are complicated by the fact that the adult stage of the worm is most active at night, and the infestation is only detected after the damage has been done,” said Icipe scientist Charles Midega.